• TheDudeV2@lemmy.ca
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    4 days ago

    I’m not a geologist but I’ve read up on it a fair bit.

    This Mars photo appears to be sandstone.

    On earth sandstone is usually associated with ancient rivers, lake shores, and sea shores. But also sand dune fields.

    The thing with sandstone though, is it’s not just sand. Rather, it’s sand plus time plus pressure plus cementation.

    Now, the time part is obvious. What’s sandstone now was sand a long ass time ago (usually).

    Pressure? That’s a little harder to understand for me here. Has mars ever had tectonic stuff going on to bury it (and hence have pressure applied), followed by erosion and uplift? Or am I incorrect and pressure is not a necessary condition? Maybe sandstone without pressure is a thing it’s just weaker and/or less dense? Maybe layers of volcanic basalt or something could have a similar effect? I don’t know and would love to have someone more knowledgeable fill this part out.

    Cementation? This part, I’m nearly certain, REQUIRES water. On earth anyway, this happens when ground water absorbs chemicals from other rock/stuff (for example carbonates from sea shells, but there’s lots of other chemicals that can do this), then flows through the beds of buried sand, and some of those chemicals are deposited along with magical chemistry stuff happening, and your sand becomes sand stone.

    So I don’t 100% know that the short answer to your question is “yes”, but I’m leaning towards a solid “yeah, probably, but I’m not a real geologist and Mars isn’t a real Earth so I dunno”.

    • cynar@lemmy.world
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      3 days ago

      Apparently, sandstone takes FAR less time to form than most people think. Apparently, some sandstone deposits have been found with roman artefacts inside. They were normal sand at the time and turned to sandstone since then.

      Basically, it would take far less time than you would think to form sandstone on Mars. It’s still proof of liquid water, but the lower end of the time estimate can be FAR shorter than you first think.